fix: Implement setting values on macOS

[httnn]

this wasn't previously implemented apparently because VoiceOver doesn't support it directly. however, there are other tools (like the Accessibility Inspector) that are able to set values so i think it's useful for at least building UI automations.

tested manually and confirmed to work!

fixes #612

[DataTriny]

Thanks @httnn, this looks like a good start. You're absolutely right, we should try to not solely focus on what VoiceOver needs.

However I don't think this method is only used to set text value. Have you had a look at how Chromium handles it? If not, this might help you start browsing the code.

[httnn]

i though i saw somewhere in the Apple documentation that this method would only accept NSString, but i can't find it anymore. must have hallucinated it! the method indeed accepts any type of value. from what i've gathered, the method is only called with text and numbers in reality, so maybe i should just make it accept an NSObject again and add support for numbers too?

[DataTriny]

from what i've gathered, the method is only called with text and numbers in reality

This was my conclusion too.

maybe i should just make it accept an NSObject again and add support for numbers too?

This would be appreciated, if you don't mind.

[httnn]

this should do it. required temporarily backporting downcast_ref from objc2 0.6: https://docs.rs/objc2/latest/objc2/runtime/struct.AnyObject.html#method.downcast_ref but other than that pretty straightforward.

[DataTriny]

Were you able to test setting a numeric value on a slider for instance.

The backporting is indeed annoying, I hope we can get rid of it soon.

[httnn]

Were you able to test setting a numeric value on a slider for instance.

yes. using the Accessibility Inspector, when the node has a numeric value, setAccessibilityValue is called with an NSNumber, and with NSString otherwise.

[DataTriny]

Thanks @httnn,

CI is reporting formatting issues. Please run cargo fmt and make sure to address any warnings you might get by running cargo clippy.

After that it will be good to merge.

[httnn]

should be formatted now!

[mwcampbell]

@httnn Thank you for this contribution. In is_selector_allowed, can you please change the logic for setAccessibilityValue: to allow either the old condition or your new one? That way, if a text input implementation doesn't actually support the SetValue action, we still get the expected behavior out of VoiceOver. Thanks again.

[httnn]

@mwcampbell ah didn't realise that the previous condition was still necessary. what exactly is the expected VoiceOver behaviour that the previous condition enables (i.e. how does it manifest)?

[DataTriny]

Thanks @httnn for your contribution,

@mwcampbell was right. Sorry for my last comment.